The relay technology intended to improve a link capacity and increase a cell coverage area is one of core technologies for a Long Term Evolution-Advanced (LTE-Advanced) system. Radio signals are transported between a Route Node (RN), an eNodeB (eNB) and a User Equipment (UE) to extend effectively a coverage area of the eNB. FIG. 1 illustrates an implementation environment thereof, where the route node amplifies and forwards the received radio signals to compensate for a propagation loss of the radio signals, in order to improve the power of the radio signal received by the eNB and/or the UE and improve the capacity of a relay link.
An effective method of improving the capacity of a relay link is the technology of cooperative diversity between the eNB and the RN as illustrated in FIG. 2 or between a plurality of RNs as illustrated in FIG. 3 dependent upon different radio environments. Of course, the technology of cooperative diversity can be implemented in a variety of technical solutions and the following description will be presented by taking the downlink as an example.
1. Mutual coordination is performed between the eNB and the RN or between the RNs through distributed space-time coding, and a transmission diversity gain is obtained at the UE side; or the UE may listen to and acquire transmission signals of the eNB and the RN(s) respectively and acquire a temporal diversity gain through maximum ratio combining.
2. A diversity gain and a coding gain are acquired between the eNB and the RN or between the RNs through coordinated coding.
Another effective method of improving the capacity of a relay link is to multiplex resources so that the eNB may be configured with a plurality of RNs dependent upon the demand and actual deployment of a system. In view of limited transmission power of the RNs, resource multiplexing may be used for the different RNs sufficiently far away from each other to improve the average spectrum efficiency and throughput of a cellular cell and further improve the capacity of the relay link, as illustrated in FIG. 4.
However, in the prior art, resource multiplexing and cooperative diversity pose sharply different requirements on a radio link: in a system, co-channel interference shall be as little as possible for the solution of resource multiplexing, that is, propagation losses of resource-multiplexed RNs or eNBs to the same UE shall differ as significantly as possible; and signal-to-noise ratios of cooperative RNs or eNBs shall be as approximate as possible for the solution of cooperative diversity, that is, propagation losses of the RNs or eNBs of cooperative diversity to the same UE shall differ as little as possible.
The existing LTE-Advanced system purely relies upon cooperative diversity or resource multiplexing to provide an access service. In the system for which cooperative diversity is adopted alone, balanced signal-to-noise ratios of cooperative links are required for cooperative diversity, and this is dependent upon the position of the UE, so there is a limited scope of applications; and an improvement to the average spectrum efficiency and throughput of a cell is limited due to a radio resource loss caused by relay forwarding. In the system for which resource multiplexing is adopted alone, the RNs have to be deployed according to a sophisticated rule but may be constrained to some extent under a practical deployment condition, so it may be difficult to fully multiple resources between the RNs.